Aerobic landfill bioreactor

Abstract

The present invention includes a method of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120° F. and 140° F. in steady state.

What is claimed is: 
     
       1. A method for operating a landfill, said landfill having a waste mass covered with a cap and a leachate collection system for collecting leachate from said waste mass in said landfill, said method comprising the steps of: dripping leachate from a leachate injection system into said waste mass;   combined vertical and horizontal injecting air into said waste mass;   adjusting said air and said leachate in said waste mass so that said temperature of said waste mass is between approximately 120° F. and approximately 140° F.; and   reducing waste density so that said waste allows improved operation.   
     
     
       2. The method as recited in claim 1, wherein dripping said leachate is adjusted so that the moisture content of said waste mass is roughly 40% to 60% by weight. 
     
     
       3. The method as recited in claim 1, wherein said dripping step further comprises the steps of: saturating said waste mass; and then reducing said moisture content to roughly 40% to 60% by weight.   
     
     
       4. The method as recited in claim 1, wherein said leachate injection system includes an array of drip emitters deployed across the surface of said cap, said drip emitters penetrating through said cap, and wherein said dripping step further comprises the step of dripping said leachate through said array of drip emitters so that said leachate is applied to said waste mass. 
     
     
       5. The method as recited in claim 1, wherein said leachate collection system includes cleanout ports and wherein said air injection step further comprises the steps of: blowing air into said cleanout ports; and   filtering said air.   
     
     
       6. The method as recited in claim 1, wherein vertical wells are bored in said landfill and said method further comprises the step of injecting additional air into said waste mass through said vertical wells, said additional air augmenting and distributing the vertical and horizontal air injected in said waste mass. 
     
     
       7. The method as recited in claim 1, further comprising the step of compacting said waste mass to a density when compacted is less than the usual 1300 lbs per cubic yard such that the mass remains physically stable and provides for improved air and water flow throughout the waste mass. 
     
     
       8. A method for converting an anaerobic landfill to an aerobic landfill for decomposition of a waste mass, said method comprising the steps of: modifying existing soil cover over said waste mass;   establish an array of holes through said cover;   establishing an array of drip emitters on the surface of said cover, each drip emitter positioned near one of said holes in said cover to drip into said waste mass through said cover;   collecting leachate from said landfill in a leachate system, said leachate system having collection ports;   connecting said array of drip emitters to said collected leachate so that said drip emitters can drip leachate into said waste mass;   connecting blowers to said cleanout ports;   blowing air into said cleanout ports at a pressure sufficient to suffuse said portion of said landfill with air;   continuing said blowing of air and dripping of leachate into said waste mass until the temperature of said waste mass is between 120° F. and 140° F.;   adding vertical air injection to achieve said temperature;   removing said cover; and   compacting said portion of said landfill upon completion of aerobic decomposition of said portion.   
     
     
       9. The method as recited in claim 8, further comprising the step of saturating said waste mass with leachate from said drip emitters and then allowing the moisture level of said waste mass to be reduced to roughly 40% to 60% by weight. 
     
     
       10. The method as recited in claim 8, wherein said compacting step is done up to a density when compacted is less than the usual 1300 pounds per cubic yard, such that the mass remains physically stable. 
     
     
       11. The method as recited in claim 8, further comprising the step of monitoring acidity, TKN, BOD, COD, metals, and VOCs in said leachate. 
     
     
       12. The method as recited in claim 8, further comprising the steps of: monitoring the level of oxygen in said waste mass; and   increasing the amount of air injected into said waste mass whenever said oxygen level begins to decrease while maintaining a moisture level in said waste mass of roughly 40% to 60% by weight.   
     
     
       13. The method as recited in claim 8, further comprising the steps of: monitoring said temperature of said waste mass; and   adding additional leachate and air whenever said temperature begins to increase beyond 140° F.